Leptospirosis is a zoonosis which has a global distribution. The disease is still an enigma 130 years post discovery. Leptospirosis is mainly a disease of the animals like the rodents and various other animals, wherein man is an accidental host. Leptospira is a spirochete, which to be visualised in a dark field microscope or in a light microscope after special staining techniques. It is a slow growing organism and requires special media like the Fletcher`s medium. Leptospirosis results when the person comes in contact with the organism either as an occupational hazard or during avocational exposure or during floods. The pathogenesis of leptospirosis is incompletely understood. Despite years of speculation, the route and mode of entry of leptospires in natural infections is not clear. The site of entry into host is through mucosal surfaces. Important portals of entry are fresh or partially healed abrasions of the skin and intact mucosa of the buccal cavity, nasal passages or conjunctiva. The disease can be seen in two forms, the mild anicteric form and the severe icteric form also known as Weil`s disease. The diagnosed leptospirosis cases are just the tip of the iceberg; many go undiagnosed due to the protean manifestations of the disease. The drug of choice for treatment is Penicillin. Vaccines are available for animals. An approved vaccine for humans is still awaited.